It is fairly easy
Create 2 Playlists ... one for each Ipod (you can create a folder for each iPod and put multiple playlists in each also)
Plug in 1st iPod
Select iPod and go to the Music Tab
Check the Sync Music box and the Selected Playlists option
Now you can just tick the checkboxes for the playlists associated with the iPod
Sync & disconnect
Repeat process with 2nd iPod .. selecting alternative playlists ..
DONE!!